After Danah Boyd, an expert on teen behavior online, finished her talk about the hyper-fragmented world of social media and messaging apps today, some adults in the audience at South By Southwest may have breathed a sigh of relief.

That’s because it’s the adults who are misbehaving, said Boyd. Her new book, “It’s Complicated: Teen’s Social Media Practices,” came out in February.

Using ephemeral messaging service Snapchat to sext is largely an adult phenomenon, Boyd said. Teens use it mostly for inside jokes.

Asked why teens do so much bullying online, Boyd had a simple answer: Adults are mean in real life; teens are just mimicking that behavior digitally.

What about new teen texting acronyms? Are parents being irresponsible if they don’t keep up with them?

“Teens really make up their own acronyms within social groups and within the app,” said Boyd. “So, you won’t ever really be able to learn the acronyms.”

In other words, surrender Dorothy (look it up).

Boyd said that what young people are really trying to do online is to be a part of public life, engaging in a new kind of “flâneur” behavior — broadly meaning one who saunters. This is, she noted, not so different from what previous generations have done.

“The fundamental practices — to communicate with friends, to be social and flirt and hang out — do not change,” she said.

Of course, there were the inevitable advertising questions, too. What are the implications for marketing if teens communicate underground? Why are teens so resistant to ads when they message? Will teens respond to brands and build communities around them?

Teens do think it’s weird when there are ads in their private messages, Boyd said. And when they acknowledge ads, sometimes it’s messier than marketers think.

For example, when teens realized Facebook posts in which brands were mentioned rose higher in the social network’s News Feed, they began adding brand names like Nike to the end of everything.

But such behavior isn’t always a boon for marketers. Boyd said she had to explain to Coca-Cola executives that much of their social media popularity has to do with another kind of coke (no need to look that one up).

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